Enhanced photocatalytic hydrogen production activity of chromium doped lead niobate under visible-light irradiation

A series of Cr-doped layered HPb2Nb3O10 was prepared by a solid-state reaction followed by H+ exchange for the first time. The effects of doping on the structural and optical properties were comprehensively characterized by powder X-ray diffraction, UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy, photoluminescence (PL) spectroscopy and scanning electron microscopy. Crystal structure was slightly adjusted by Cr3+ substituting for Nb5+. Absorption edge of the photocatalyst gradually red shifted with the increase of Cr3+, indicating the narrowing of band gap. Photocatalytic hydrogen evolution activity of Cr-doped HPb2Nb3O10, under full-arc or visible-light irradiation, gradually increased with Cr content up to 0.05 and thereafter decreased with higher Cr content. The activity of Cr(0.05)-doped HPb2Nb3O10 was twice as high as that of undoped HPb2Nb3O10. Narrower band gap and higher separation efficiency of photoinduced carriers in the bulk are the key factors that lead to its superior photocatalytic performance. (C) 2013 Elsevier B.V. All rights reserved.